Industrial blenders for mixing bulk material are well known in the art. A typical application for such blenders is the mixing of color pigments or the provision of plastic pellets such as those required as raw material for the plastics processing industry. This type of mixing vessel is a steel vessel with a spheroidal cross-section. The vessel has a feed opening on its upper side and a vessel flange that projects outward in the area of its upper end. Such a mixing vessel normally has an upper cylindrical section with an adjacent conical section facing downward which tapers the internal diameter of the mixing vessel like a funnel to the discharge duct on the bottom section.
A discharge flap valve is mounted on a swivel axis within the discharge duct and can be adjusted between an open position and a closed position, and vice versa. The discharge duct also typically has a circular cross-sectional area. The discharge flap valve, which has an outer contour that is correspondingly circular or somewhat oval, has a gasket on its outer perimeter that seals the discharge flap valve against the inside wall of the discharge duct in the closed position. The mixing vessel is then sealed.
The flange of the mixing vessel is connected with the complementary flange of a mixing head of an industrial blender to mix the materials. The mixing head itself has one or more mixing tools. Once the mixing vessel filled with the material to be blended is connected to the mixing head, the entire unit is rotated by 180° such that the mixing head is at the very bottom and the mixing vessel is at the very top. In this position, the material to be blended in the mixing vessel first drops onto the mixing tools. Thus the mixing chamber in which the material is mixed is formed by the cavity provided by the mixing vessel and that provided by the mixing head. At least one mixing tool is driven in a rotational direction to perform the mixing operation and generates a flow of blended material within the mixing space formed by the mixing vessel and the mixing head. The mixing space is shaped to allow good rotational flow of the material to be mixed in a known manner. As a rule, a certain amount of heat input into the mix is unavoidable during a mixing operation, particularly due to the shear forces occurring between the mixing tool(s) and the particles of the mixture, but also when mixture particles impact against the inner wall of the mixing vessel. This sometimes leads to material build-up on the mixing vessel wall, particularly in those areas impacted by the mixed material flow.
Such industrial blenders are typically used for mixing different mixtures. Largely as a result of the potential caking mentioned above, any blender components coming into contact with the mixture must be cleaned before they are used for a different mixture. Depending on the size and the type of blended material, the time required for cleaning the mixing vessel alone can be as long as 1-2 hours. Cleaning the mixing head is much easier, however, because caking on its walls is highly unlikely. Moreover, the mixing tool(s) can be easily removed and cleaned outside of the mixing head. Cleaning the inner surface of the mixing head is also significantly easier than cleaning the inside of the mixing vessel.
The foregoing example of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.